Various kinds of silver halide photographic materials are now sold in the commercial market and various methods for processing them are known. They are utilized in various technical fields. Of such photographic materials, those for color photographic paper products which are used in the market where a large amount of color prints are needed to be finished within a short time of delivery to consumers contain silver bromide or silver chlorobromide and which do not substantially contain silver iodide.
Recently, improvement of the rapid processability of color photographic papers is increasingly requested, and many studies thereon have been made. It is known that elevation of the silver chloride content in a silver halide emulsion to be used for preparing a color photographic paper brings about a drastic improvement or acceleration of the developability of the paper. In fact, in the market, use of a high silver chloride emulsion in preparing commercial color photographic papers has been promoted.
On the other hand, for processing color photographic papers, not only the rapid processability but also the processing stability is required. Namely, where a large amount of color prints are continuously processed, a small fluctuation of the photographic properties of the processed prints is desired before and after continuous processing. Recently, in particular, reduction of the amount of the replenisher to be added during processing of photographic materials is desired for the purpose of saving natural resources and of reducing environmental pollution. Also, from the point of new of, provision of photographic materials for color printing papers, photographic properties which hardly fluctuate before and after continuous processing is important. JP-A-1-167752 has disclosed a technique of reducing fluctuation of the photographic properties of photographic materials before and after continuous processing, by incorporating auxiliary silver halide grains which are not substantially developed in a non-light-sensitive layer. (The term "JP-A" as used herein means an "unexamined Japanese patent application".) In accordance with the disclosed technique, however, the improving effect is not always sufficient.
In addition, color photographic papers are also needed to be able to form images of high image sharpness. In particular, use of printing computer graphic images, line images or letter images in color photographic papers, in addition to the ordinary use of printing ordinary color images, such as portraits or landscapes is increasing. Therefore, the demand for obtaining images with high image sharpness in color photographic papers is ever-increasing. It is well known that the image sharpness of images to be formed in color photographic materials may well be elevated by inhibiting irradiation or halation by incorporating dyes or colloidal silver into the materials. However, incorporation of them is known to involve a depression in the sensitivity of the materials. In order to prevent this drawback, high-sensitivity silver halide emulsions must be used for preparing the materials. Heretofore, silver halide emulsions having a high silver chloride content which are suitable for rapid processing could hardly produce high-sensitivity photographic materials. In order to improve the high-sensitivity photographic materials using silver halide emulsions having a high silver chloride content, various techniques have heretofore been proposed and disclosed.
Examples include JP-A-58-85736, JP-A-58-108533, JP-A-60-222844, JP-A-60-222845 and JP-A-64-26837 which illustrate and demonstrate that photographic materials containing high silver chloride emulsions which have a silver bromide rich-region of various constitution and which have been sulfur-sensitized have high sensitivity and hard photographic property. In accordance with the illustrated techniques, high-sensitivity emulsions could be obtained, however, the photographic materials containing such high-sensitivity emulsions disadvantageously involve a noticeable fluctuation in the photographic properties before and after continuous processing thereof.
The present inventors investigated the above-mentioned problems and, as a result, found that tellurium-sensitized high silver chloride emulsions may form high sensitivity silver halide photographic materials having excellent continuous processability. Tellurium sensitization kind of chalcogen sensitization. However, such tellurium sensitization is not widely known, though sulfur sensitization and selenium sensitization have heretofore been investigated in detail in this technical field. For instance, a tellurium sensitization method and tellurium sensitizing agent are generally disclosed in U.S. Pat. Nos. 1,623,499, 3,320,069, 3,772,031, 3,531,289, 3,655,394, 4,704,349; British Patents 235,211, 1,121,496, 1,295,462, 1,396,696, 2,160,993; Canadian Patent 800,958; and JP-A-61-67845. However, detailed and concrete descriptions relating to tellurium sensitization are only in British Patents 1,295,462 and 1,396,696, and Canadian Patent 800,958. Thus, the technology of application of tellurium sensitization of a silver halide emulsion having a high silver chloride content to yield a silver halide photographic material having a high sensitivity and excellent continuous processability, as in the present invention, is not known at all.
When a tellurium-sensitized high silver chloride emulsion was used in forming a photographic material and the material was tested for practical use, it has been found for the first time that the material involves a serious drawback with respect to the exposure humidity dependence. Namely, it has been determined that when the ambient humidity during exposure of the photographic material is high, then the depression in the image density with respect to the image to be formed in the material is large.